Difference between revisions of "Improved Cookstoves and Energy Saving Cooking Equipment"

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[[GIZ HERA Cooking Energy Compendium|--> Back to Overview GIZ HERA Cooking Energy Compendium]]
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{{HERA Banner}}
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=== Introduction ===
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[[File:Rocket Stove Malawi.jpg|border|right|150px|Rocket Stove Malawi.jpg|alt=Rocket Stove Malawi.jpg]]Research, dissemination, and commercialization efforts over the past few decades have brought a range of improved charcoal and also wood-burning stoves into use. Many of these stove models, as well as the programs and policies that have supported their commercialization, have been highly successful.
 +
 
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It is difficult to get regional or even global data on improved stoves sales or use. The [http://cleancookstoves.org/|Global Alliance for Clean Cookstoves] is the only stakeholder, which is collecting such data on a global scale from her member organizations and companies.<br/>In 2013, 14, 3 million stoves were disseminated by partners of the Global Alliance for Clean Cookstoves, including LPG stoves, biogas stoves, etc. Almost one third of them in Africa, over 60% in Asia and 6% in Latin America. Two thirds of the distributed stoves were portable.<ref name="Global Alliance for Clean Cookstoves: Results Report 2013. http://cleancookstoves.org/binary-data/RESOURCE/file/000/000/285-1.pdf"> Global Alliance for Clean Cookstoves: Results Report 2013. http://cleancookstoves.org/binary-data/RESOURCE/file/000/000/285-1.pdf</ref> In 2014, 20 million stoves and fuels were reported, out of which 12 mio. were classified as clean and/or efficient. Fuel volumes were converted into household “stove equivalents”, representing the number of households the reported volume of fuels could supply.<ref name="Global Alliance for Clean Cookstoves: Results Report 2014. http://cleancookstoves.org/resources/414.html">Global Alliance for Clean Cookstoves: Results Report 2014. http://cleancookstoves.org/resources/414.html</ref>
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The following text provides some definitions and explanations around improved cookstoves.
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Watch the video from Ashden Awards below to get a short introduction about cooking energy and improved cookstoves.
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{{#widget:YouTube|id=Yu5SdH2_0JU|height=400|width=600}}
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===Household Cooking Energy Diversity===
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Household cooking energy is often discussed as a “one fuel - one stove” system. The archetype of this idea is the rural household using firewood in a 3-stone fireplace. On a second look, this picture is often a drastic simplification of the reality. Many households, particularly in (peri-) urban environments, are actually using several fuels and several stoves for a variety of reasons:
 +
 
 +
* The cooking of different food requires different types of heat.
 +
*Seasonal variation of availability or affordability of fuels (e.g. biomass as back-up if fossil fuels or electricity is not available, increasing prices or money shortages at the end of the month);
 +
*Variation of convenience needs (e.g. fast cooking in the morning, slow cooking in the evening);
 +
* Different abilities of cooks using a stove (e.g. expensive fuels and stoves shall not be used by the young daughter, so she is using firewood);
 +
*Different cooking needs (e.g. preparation of meals for the family on a different stove as the preparation of animal feed or processed food for the market);
 +
*Different types, shapes and sizes of cooking utensils (cooking pots, pans etc.) require different stove shapes or sizes.
 +
 
 +
 
 +
Cooking energy interventions should be based on a clear understanding of the household <span style="color:#FF0000">cooking energy diversity of their target groups before activities are planned</span>. It must be clear which part of the “traditional” (= baseline) cooking system shall be addressed.
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=== The Cooking Energy System===
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Users not only make choices on ‘stoves and fuels’, they also decide on which meal to prepare, which cooking equipment to use and, most important, how to cook.
 +
 
 +
Thus, cooking in households is a complex system, which comprises different factors related to fuel and cooking device, as well as to user behaviour, cooking equipment and environment. &nbsp;
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For more information read the article <span style="color:#FF0000">[[The Cooking Energy System]]</span>.<br />
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===What is a Stove?===
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The term ‘stove’ refers to a device that generates heat from an energy carrier and makes that heat available for the intended use in a specific application. Cook stoves are made to transfer the generated heat to food, with the purpose to get it cooked, refined etc. and therefore edible for human consumption. Thus a ‘stove’ features the '''combination of heat generation and heat transfer''' to a cooking pot if the food is cooked in a liquid, or a griddle, plancha etc. if the food is baked on a hot surface or roasted without liquid.<br />
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[[File:Stove scheme GIZ HERA.jpg|x258px|alt=Stove scheme GIZ HERA.jpg|right]]<br />
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<br />
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= What is a stove? =
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===What is an Improved Cookstove (ICS)?===
  
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Commonly the term ‘stove’ refers to a device that generates heat from an energy carrier and makes that heat available for the intended use in a specific application. Cook stoves are made to transfer the generated heat into food, with the purpose to get it cooked and edible for the human consumption. Thus ‘a stove’ always features the '''combination of heat generation and heat transfer''' into a <u>cooking pot</u> if the food is cooked in a liquid, or a<u>griddle, plancha</u> etc. if the food is baked on a hot surface or roasted without liquid.
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Cookstoves are commonly called “improved” if they are more efficient, emit less emissions or are safer than the traditional cook stoves or three-stone-fires. The term usually refers to stoves which are burning firewood, charcoal, agriculture residues or dung.<ref name="http://www.forestrynepal.org/wiki/117">http://www.forestrynepal.org/wiki/117</ref><ref name="http://www.climatetechwiki.org/technology/imcookstoves">http://www.climatetechwiki.org/technology/imcookstoves </ref>
  
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= What is an efficient stove? =
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'''Energy efficiency '''describes the heat transferred into the pot in relation to the overall energy generated by the stove within a defined task (e.g.<span style="color:#FF0000">[[Stove_Testing_and_Measurement|Water Boiling Test, WBT]]</span>). A higher efficiency can i.e. be achieved by:<ref name="http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf">http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf </ref><ref name="Improved Cookstoves, HEDON, http://hedon.info/ImprovedCookstove&highlight=classification">Improved Cookstoves, HEDON, http://hedon.info/ImprovedCookstove&highlight=classification </ref>
  
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Cook stoves are commonly called “improved” if they are more “efficient” as the traditional cook stoves. But what does “efficient” mean in this case?
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*Better combustion of the fuel by providing an insulated combustion chamber around and above the fire, which leads to a better mixing of gases, flame and air. This enhances the temperature of the fire with the following consequences: faster water boiling, fuel use reduction, and decreases in CO and PM.
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*Maximum transfer of heat of combustion from the flame and the hot gases to the cooking pot.
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*Minimum loss of heat to the surroundings.
  
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The actual energy efficiency describes the heat transferred into the pot in relation to the overall energy generated in the stove within a defined task (e.g. water boiling test). For more details on stove testing see [[Testing of woodfuel stoves|here]].
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'''Specific fuel consumption '''describes the fuel used per unit of food cooked or boiled water, e.g. how much wood was used to cook a liter of beans.<ref name="http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf"> http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf</ref>
  
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But in most cases, this is not what is meant when the efficiency of stoves is discussed. From the perspective of a stove user, the core question concerning the efficiency of two alternative stoves is:<br/>“With which of the two stoves do I use less fuel to prepare my meal?”

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When we talk about the efficiency of stoves, we usually compare the '''specific fuel consumption''' of a specific stove to either (a) a benchmark or (b) the specific consumption of another stove.
  
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To answer this question, the perspective of energy efficiency is too narrow as a number of factors beyond the stove design take influence:
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<u>Examples:</u>
  
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*the quality and characteristics of the fuel,
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*Stove A consumes less fuel for a specific standardized task as indicated in the benchmark (e.g. 80g of charcoal per kg food prepared in a controlled cooking test)
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*the handling of the fuel,
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*Stove A consumes 40% less fuel than stove B per litre boiled water (e.g. compared by a 5l Water Boiling Test)
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*the handling of the stove,
 
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*the management of the cooking process
 
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*the environment of cooking…
 
  
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In this broader sense it is a cooking system that has to be analysed to determine which stove has a higher “user efficiency”.
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With focus on relative performances of stoves, the assessment of stove efficiency is circumstantial. A simple portable clay stove is perceived as an efficient stove in households with open fire places and as an inefficient stove in households which are using a rocket stove.<br />For international standards on stove quality that are currently being developed by the International Organisation for Standardisation (ISO) see the article <span style="color:#FF0000">[[Standards for Improved Cookstoves]].</span>
  
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When we talk about the efficiency of stoves, we usually mean the comparison of the specific fuel consumption of a specific energy use in comparison to either (a) a benchmark or (b) the specific consumption of another stove.<br/>Examples:
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<br />
  
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*(a) Stove A consumes less fuel (for a specific standardised task) as indicated in the benchmark (e.g. 80g of charcoal per kg food prepared in a controlled cooking test);
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'''Lower emissions''' than baseline stoves or open fires emit are further characteristics of improved stoves. Emissions are byproducts from the incomplete combustion of fuel that are discharged into the air. They can be very harmful for human health and environment. Chimney stoves address the problem of indoor air pollution very effectively, because they lead all emissions to the outside. However, it is important to use a stove with good draft. If smoke can flow out of the fuel entrance, or leak in other ways into the room, harmful emission levels will rise. Even some stove designs have fewer emissions than others, the fuel properties still have a big influence: even the best stove can hardly burn <span style="color:#FF0000"></span>[[Cooking with Firewood|wet wood]] properly.<ref name="http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf">http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf </ref>
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*(b) Stove A consumes 40% less fuel than stove B per litre boiled water (in a 5l Water boiling test);
 
  
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With focus on relative performances of stoves, the assessment of stove efficiency is circumstantial. A clay stove is perceived as an efficient stove in households with open fire places and as an inefficient stove in households which are using a rocket stove.<br/>International standards on stove quality have been discussed for many years. While they are desirable to enable a global comparison of stove performances, there is a danger that cheap solutions for the very poor households are abandoned due to their low performance in relation to the global standards, when in fact they could still be a relevant improvement in comparison to the baseline situation of the poorest of the poor. That’s why a stratification of quality standards has been developed in the [http://www.pciaonline.org/presentations/lima-consensus-full-document Lima consensus].
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Safety can be another aspect of improved stoves. This means, for example, no open flames are leaving the stove, the stove is not easy to tip, and stove parts that need to be touched during cooking are not getting too hot and cause burnings.<ref name="Biomass Stove Safety Protocol BSSP 1.1 Protocol (English)">Biomass Stove Safety Protocol BSSP 1.1 Protocol (English)</ref>
  
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= Global stove diversity&nbsp;<br/> =
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Improved cookstoves (ICS) can take many shapes: they can be portable or fixed installed in a kitchen; they can be made of different materials such as metal or clay; they come with or without a chimney; and they can have different sizes for households, institutions or small enterprises.
  
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There are many different types of stoves on this planet. This is natural, as a stove needs to accommodate the site-specific constellation determined by the available fuels, climatic conditions and preferences of users in the local culture. Thus stove designs reflect global diversity. Please keep in mind: ‘One size fits some, but rarely all’.
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Regarding ICS for fuelwood, savings between 25-65% per stove per household are realistic when used correctly, while improved charcoal stoves usually save around 25-35% compared to traditional charcoal stoves.<ref name="ESMAP (2015): The State of the Global Clean and Improved Cooking Sector. https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf">ESMAP (2015): The State of the Global Clean and Improved Cooking Sector. https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf</ref>
  
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The resulting diversity of stoves can be described in different categories like
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<br />
  
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*Fuel types (solid, liquid or gaseous fuels from renewable biomass or fossil sources)
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However, be aware that not all so-called “improved“ stoves are really saving energy or emit less harmful smokes. Sometimes, stoves that are designed to be more efficient are in reality less efficient than the prevailing technology or emit higher levels of emissions. Only proper stove testing not only in laboratories but in existent kitchens with real users (field test) can show how improved an “improved” stove really is.<ref name="http://www.scientificamerican.com/article/improved-cookstoves-little-reduce-harmful-indoor-emissions/">http://www.scientificamerican.com/article/improved-cookstoves-little-reduce-harmful-indoor-emissions/</ref>&nbsp;Furthermore, over the years and with constant use, ICS can get weaker in their performance by losing efficiency and higher emissions due to bad maintenance, material fatigue and wrong usage.
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*Pot sizes (from small to big individual households sizes, medium to large pots for restaurants, enterprises or social institutions)
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===What is an Advanced Cookstove (ACS)?===
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*Pot shapes and materials (round bottom/flat bottom pots, clay or metal, pots with or without handles and/or legs, frying pans,&nbsp; etc.)
 
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*Numbers of pots to be used at a time (pot holes for one or several saucepans)
 
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*Numbers of fires (one fire-box or several fires)
 
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*Batch-feeding or continuous feed of fuel
 
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*Natural draft or forced convection with a ventilator
 
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*With or without a built-in chimney to remove emissions from a kitchen
 
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*Transportability (from built-in models that have to be constructed on site to portable stoves built elsewhere)
 
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*Affordability (to suit the range of economic means of users from low-cost to more expensive)
 
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*Place of manufacture (national production or imported)
 
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*Cost (mainly determined by the type of building material and the level of sophistication of a stove)
 
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*Other uses of a stove e.g. space heating, lighting
 
  
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<br/>Stove designs also depend on the cooking habits. For instance, in many Latin American countries tortillas are a traditional staple food baked on a hot metal plate ('plancha'). In Ethiopia the staple food is a pancake baked on a large ceramic plate. Any stove needs to incorporate those features that are essential for people to prepare their staple foods. Otherwise the stove will not be acceptable in that area.
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Advanced stoves are very high performing cookstoves, which emit very low emissions, are very efficient and also very safe in use. Basically, these are gasifier stoves and forced air stoves, both working with processed or raw biomass.<ref name="https://en.wikipedia.org/wiki/Cook_stove#Advanced_biomass_cookstoves">https://en.wikipedia.org/wiki/Cook_stove#Advanced_biomass_cookstoves</ref><ref name="Practical Action (2013): Technical Brief. Gasifier Stoves - Advanced Biomass Stoves. http://answers.practicalaction.org/our-resources/item/gasifier-stoves-advanced-biomass-stoves">Practical Action (2013): Technical Brief. Gasifier Stoves - Advanced Biomass Stoves. http://answers.practicalaction.org/our-resources/item/gasifier-stoves-advanced-biomass-stoves </ref>
  
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Beatrix Westhoff and Dorsi German compiled a comprehensive overview on global stove diversity in 1995 in the publication 'Stove Images - a Documentation of Improved and Traditional Stoves in Africa, Asia and Latin America'. It is available in English, French and Spanish on
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*'''Forced air stoves''' have a fan powered either by a battery, an external source of electricity, or a thermoelectric generator. This fan blows high velocity, low volume jets of air into the combustion chamber that mix fuel, air and flame. Mixing results in more complete combustion of the fuel and dramatically reduces pollution.<ref name="Global Alliance for Clean Cookstoves, http://cleancookstoves.org/technology-and-fuels/stoves/">Global Alliance for Clean Cookstoves, http://cleancookstoves.org/technology-and-fuels/stoves/ </ref><ref name="http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf">http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf </ref>
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*'''[[Gasifier Stoves|Gasifier stoves]]'''&nbsp;force the gases and smoke that result from incomplete combustion of fuels such as biomass back into the cookstove's flame, where the heat of the flame then continues to combust the particles in the smoke until almost complete combustion has occurred, reducing emissions. Typical gasifier stoves are known as Top Lit Updraft (TLUD) stoves because some fuel is lit on top of the stove, forcing combustible products to pass through the flame front before being emitted into the air. Gasifier stoves can also include a fan, to improve mixing of flame, gas, and smoke and to reduce emissions.<ref name="http://carbonfinanceforcookstoves.org/about-cookstoves/cookstoves-and-fuels/">http://carbonfinanceforcookstoves.org/about-cookstoves/cookstoves-and-fuels/ </ref>
  
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*[http://www.gtz.de/en/themen/umwelt-infrastruktur/energie/32777.htm http://www.gtz.de/en/themen/umwelt-infrastruktur/energie/32777.htm]
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<br />
  
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Not all stove types comply with criteria required to qualify as 'improved stoves'.<br/>Promising stove types that are performing well within the GIZ-supported project areas are presented in the '''Stove Fact Sheets '''published by GIZ HERA.
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===What is Energy-Saving Equipment?===
  
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<br/>The following chapters present stove types for different fuels and cooking practices according to the following structure:
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Energy-saving equipment are devices, which help reduce fuel consumption in addition to the used stove. These include hot-bags, in which food can continue to simmer and be kept warm, pressure-cookers and thermo-flasks. Find more information [[Energy-Saving Cooking Equipment|here]]. &nbsp;
  
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= [[File:Structure of technology and practice chapter Cooking Energy Compendium.png]]Household cooking energy diversity&nbsp; =
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=== Overview of Major Cooking Fuels and technologies ===
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Watch this webinar for an overview of major cooking fuels and technologies<br />
  
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Commonly household cooking energy is discussed as a “one fuel - one stove” system. The archetype of this idea is the rural household using firewood in a 3-stone fireplace. On a second look, this picture is often a drastic simplification of the reality. Many households, particularly in (peri-) urban environments, are actually using several fuels and/or several stoves for a variety of reasons:
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{{#widget:YouTube|id=YJ_vUJX23wE|height=400|width=600}}
  
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*Different traditional meals require different types of heat (e.g. Ethiopia: the large pancake-style injera, sauce, and coffee ceremony);
 
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*Seasonal variation of availability or affordability of fuels (e.g. biomass as back-up if fossil fuels or electricity is not available, increasing prices or money shortages at the end of the month);
 
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*Variation of convenience needs (e.g. fast cooking in the morning, slow cooking in the evening);
 
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*Different abilities of cooks (e.g. expensive fuels and stoves shall not be used by the young daughter, so she is using firewood);
 
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*Different cooking needs (e.g. preparation of meals for the family on a different stove as the preparation of animal feed or processed food for the market);
 
−
*Different types, shapes and sizes of cooking utensils (cooking pots, pans etc.) require different stove shapes or sizes.
 
  
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Cooking energy interventions should be based on a clear understanding of the household cooking energy diversity of their target groups before activities are planned. It must be clear which part of the “traditional” (= baseline) cooking system shall be addressed.
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===Further Information===
  
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= Fuel switching and the “energy ladder” =
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*[http://hedon.info/ImprovedCookstove&highlight=classification Characteristics of Improved Cookstoves]. HEDON
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*Classification of Cookstoves. Article on energypedia.&nbsp;
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*[[Stove_Testing_and_Measurement|Stove Testing on energypedia]]. Article on energypedia.&nbsp;
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*[[Standards_for_Improved_Cookstoves|Standards for Improved Cookstoves.]] Article on energypedia
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*[http://www.scientificamerican.com/article/improved-cookstoves-little-reduce-harmful-indoor-emissions/ "Improved" Cookstoves May Do Little to Reduce Harmful Indoor Emissions]. In Scientific American, July 11, 2012
 +
*[http://www.biochar-international.org/sites/default/files/Understanding-Stoves-okt-10-webversion.pdf Understanding Stoves]. By Sai Bhaskar N. Reddy (2012)
 +
*Cleaner Hearths, Better Homes. New stoves for India and the Developing World. By Douglas F. Barnes et al. (2012). http://cleancookstoves.org/resources_files/cleaner-hearths-better.pdf
 +
*The Clean Cooking Catalogue by the Global Alliance for Clean Cookstoves. http://catalog.cleancookstoves.org/
 +
*The State of the Global Clean and Improved Cooking Sector by ESMAP (2015). https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf
  
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A favoured development model for household energy is described with the term “energy ladder”. The basic idea is that with increasing wealth, households are ‘progressing’ from stickwood to charcoal, kerosene, LPG and finally to electricity. Each step on the ladder is linked to a fuel switch which implies in this model the permanent and complete change from the use of “traditional” fuels to more “modern” fuels.
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<br />
  
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As indicated above, the introduction of “modern” alternatives often rather contributes to an enlargement of the complexity of parallel utilised cooking systems (the “cooking energy mix”) rather than a complete fuel switch in the sense of climbing a ladder.
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=References =
  
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In recent years, more and more observations have been made that users of “modern energy” like electricity or LPG are “going down the ladder” if a removal of subsidies increases the cost of cooking and/or the availability of the fuel. Hence the picture of “switching the fuel” is in many cases rather a matter of “increasing the diversity of options” than a permanent change of behaviour.
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This article was originally published by [http://www.giz.de/fachexpertise/html/2769.html GIZ HERA]. It is basically based on experiences, lessons learned and information gathered by GIZ cook stove projects. You can find more information about the authors and experts of the original “Cooking Energy Compendium” in the [[Imprint - GIZ HERA Cooking Energy Compendium|Imprint]].<references />
  
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Generally it is easier to convince households to increase the efficiency of use of their traditional fuel(s) rather than to learn how to use a new fuel. It is also easier only to deal with the establishment of a supply-demand system for a stove rather than establishing a new fuel supply system as well. Fuel is needed on a daily basis; a stove needs to be replaced only once in a while. It sounds plausible that urban and better educated households are more open to innovations as compared to rural households with less education.<br/>However, this is a decision by the target group which can be surprisingly different than our assumptions. In a field test of a plant oil stove in Tanzania, even rural firewood using households have managed to operate a plant oil stove successfully.
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[[Improved Cook Stoves – What is it all about?#What_is_a_stove.3F|Top of the page]]
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[[#What_is_a_stove.3F|Top of the page]]
  
 
[[GIZ HERA Cooking Energy Compendium|--> Back to Overview GIZ HERA Cooking Energy Compendium]]
 
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Latest revision as of 08:41, 2 May 2022

GIZ HERA Cooking Energy Compendium small.png

Cooking Energy System | Basics | Policy Advice | Planning | Designing and Implementing ICS Supply | Designing and Implementing Woodfuel Supply | Climate Change | Extra

Introduction

Rocket Stove Malawi.jpg

Research, dissemination, and commercialization efforts over the past few decades have brought a range of improved charcoal and also wood-burning stoves into use. Many of these stove models, as well as the programs and policies that have supported their commercialization, have been highly successful.

It is difficult to get regional or even global data on improved stoves sales or use. The Alliance for Clean Cookstoves is the only stakeholder, which is collecting such data on a global scale from her member organizations and companies.
In 2013, 14, 3 million stoves were disseminated by partners of the Global Alliance for Clean Cookstoves, including LPG stoves, biogas stoves, etc. Almost one third of them in Africa, over 60% in Asia and 6% in Latin America. Two thirds of the distributed stoves were portable.[1] In 2014, 20 million stoves and fuels were reported, out of which 12 mio. were classified as clean and/or efficient. Fuel volumes were converted into household “stove equivalents”, representing the number of households the reported volume of fuels could supply.[2]

The following text provides some definitions and explanations around improved cookstoves.

Watch the video from Ashden Awards below to get a short introduction about cooking energy and improved cookstoves.

Household Cooking Energy Diversity

Household cooking energy is often discussed as a “one fuel - one stove” system. The archetype of this idea is the rural household using firewood in a 3-stone fireplace. On a second look, this picture is often a drastic simplification of the reality. Many households, particularly in (peri-) urban environments, are actually using several fuels and several stoves for a variety of reasons:

  • The cooking of different food requires different types of heat.
  • Seasonal variation of availability or affordability of fuels (e.g. biomass as back-up if fossil fuels or electricity is not available, increasing prices or money shortages at the end of the month);
  • Variation of convenience needs (e.g. fast cooking in the morning, slow cooking in the evening);
  • Different abilities of cooks using a stove (e.g. expensive fuels and stoves shall not be used by the young daughter, so she is using firewood);
  • Different cooking needs (e.g. preparation of meals for the family on a different stove as the preparation of animal feed or processed food for the market);
  • Different types, shapes and sizes of cooking utensils (cooking pots, pans etc.) require different stove shapes or sizes.


Cooking energy interventions should be based on a clear understanding of the household cooking energy diversity of their target groups before activities are planned. It must be clear which part of the “traditional” (= baseline) cooking system shall be addressed.

The Cooking Energy System

Users not only make choices on ‘stoves and fuels’, they also decide on which meal to prepare, which cooking equipment to use and, most important, how to cook.

Thus, cooking in households is a complex system, which comprises different factors related to fuel and cooking device, as well as to user behaviour, cooking equipment and environment.  

For more information read the article The Cooking Energy System.

What is a Stove?

The term ‘stove’ refers to a device that generates heat from an energy carrier and makes that heat available for the intended use in a specific application. Cook stoves are made to transfer the generated heat to food, with the purpose to get it cooked, refined etc. and therefore edible for human consumption. Thus a ‘stove’ features the combination of heat generation and heat transfer to a cooking pot if the food is cooked in a liquid, or a griddle, plancha etc. if the food is baked on a hot surface or roasted without liquid.

Stove scheme GIZ HERA.jpg




What is an Improved Cookstove (ICS)?

Cookstoves are commonly called “improved” if they are more efficient, emit less emissions or are safer than the traditional cook stoves or three-stone-fires. The term usually refers to stoves which are burning firewood, charcoal, agriculture residues or dung.[3][4]

Energy efficiency describes the heat transferred into the pot in relation to the overall energy generated by the stove within a defined task (e.g.Water Boiling Test, WBT). A higher efficiency can i.e. be achieved by:[5][6]

  • Better combustion of the fuel by providing an insulated combustion chamber around and above the fire, which leads to a better mixing of gases, flame and air. This enhances the temperature of the fire with the following consequences: faster water boiling, fuel use reduction, and decreases in CO and PM.
  • Maximum transfer of heat of combustion from the flame and the hot gases to the cooking pot.
  • Minimum loss of heat to the surroundings.

Specific fuel consumption describes the fuel used per unit of food cooked or boiled water, e.g. how much wood was used to cook a liter of beans.[5]

When we talk about the efficiency of stoves, we usually compare the specific fuel consumption of a specific stove to either (a) a benchmark or (b) the specific consumption of another stove.

Examples:

  • Stove A consumes less fuel for a specific standardized task as indicated in the benchmark (e.g. 80g of charcoal per kg food prepared in a controlled cooking test)
  • Stove A consumes 40% less fuel than stove B per litre boiled water (e.g. compared by a 5l Water Boiling Test)

With focus on relative performances of stoves, the assessment of stove efficiency is circumstantial. A simple portable clay stove is perceived as an efficient stove in households with open fire places and as an inefficient stove in households which are using a rocket stove.
For international standards on stove quality that are currently being developed by the International Organisation for Standardisation (ISO) see the article Standards for Improved Cookstoves.


Lower emissions than baseline stoves or open fires emit are further characteristics of improved stoves. Emissions are byproducts from the incomplete combustion of fuel that are discharged into the air. They can be very harmful for human health and environment. Chimney stoves address the problem of indoor air pollution very effectively, because they lead all emissions to the outside. However, it is important to use a stove with good draft. If smoke can flow out of the fuel entrance, or leak in other ways into the room, harmful emission levels will rise. Even some stove designs have fewer emissions than others, the fuel properties still have a big influence: even the best stove can hardly burn wet wood properly.[5]

Safety can be another aspect of improved stoves. This means, for example, no open flames are leaving the stove, the stove is not easy to tip, and stove parts that need to be touched during cooking are not getting too hot and cause burnings.[7]

Improved cookstoves (ICS) can take many shapes: they can be portable or fixed installed in a kitchen; they can be made of different materials such as metal or clay; they come with or without a chimney; and they can have different sizes for households, institutions or small enterprises.

Regarding ICS for fuelwood, savings between 25-65% per stove per household are realistic when used correctly, while improved charcoal stoves usually save around 25-35% compared to traditional charcoal stoves.[8]


However, be aware that not all so-called “improved“ stoves are really saving energy or emit less harmful smokes. Sometimes, stoves that are designed to be more efficient are in reality less efficient than the prevailing technology or emit higher levels of emissions. Only proper stove testing not only in laboratories but in existent kitchens with real users (field test) can show how improved an “improved” stove really is.[9] Furthermore, over the years and with constant use, ICS can get weaker in their performance by losing efficiency and higher emissions due to bad maintenance, material fatigue and wrong usage.

What is an Advanced Cookstove (ACS)?

Advanced stoves are very high performing cookstoves, which emit very low emissions, are very efficient and also very safe in use. Basically, these are gasifier stoves and forced air stoves, both working with processed or raw biomass.[10][11]

  • Forced air stoves have a fan powered either by a battery, an external source of electricity, or a thermoelectric generator. This fan blows high velocity, low volume jets of air into the combustion chamber that mix fuel, air and flame. Mixing results in more complete combustion of the fuel and dramatically reduces pollution.[12][5]
  • Gasifier stoves force the gases and smoke that result from incomplete combustion of fuels such as biomass back into the cookstove's flame, where the heat of the flame then continues to combust the particles in the smoke until almost complete combustion has occurred, reducing emissions. Typical gasifier stoves are known as Top Lit Updraft (TLUD) stoves because some fuel is lit on top of the stove, forcing combustible products to pass through the flame front before being emitted into the air. Gasifier stoves can also include a fan, to improve mixing of flame, gas, and smoke and to reduce emissions.[13]


What is Energy-Saving Equipment?

Energy-saving equipment are devices, which help reduce fuel consumption in addition to the used stove. These include hot-bags, in which food can continue to simmer and be kept warm, pressure-cookers and thermo-flasks. Find more information here.  

Overview of Major Cooking Fuels and technologies

Watch this webinar for an overview of major cooking fuels and technologies


Further Information


References

This article was originally published by GIZ HERA. It is basically based on experiences, lessons learned and information gathered by GIZ cook stove projects. You can find more information about the authors and experts of the original “Cooking Energy Compendium” in the Imprint.

  1. ↑ Global Alliance for Clean Cookstoves: Results Report 2013. http://cleancookstoves.org/binary-data/RESOURCE/file/000/000/285-1.pdf
  2. ↑ Global Alliance for Clean Cookstoves: Results Report 2014. http://cleancookstoves.org/resources/414.html
  3. ↑ http://www.forestrynepal.org/wiki/117
  4. ↑ http://www.climatetechwiki.org/technology/imcookstoves
  5. ↑ 5.0 5.1 5.2 5.3 http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf Cite error: Invalid <ref> tag; name "http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf" defined multiple times with different content Cite error: Invalid <ref> tag; name "http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf" defined multiple times with different content Cite error: Invalid <ref> tag; name "http://www.ewb-usa.org/files/2015/05/TestResultsCookstovePerformance.pdf" defined multiple times with different content
  6. ↑ Improved Cookstoves, HEDON, http://hedon.info/ImprovedCookstove&highlight=classification
  7. ↑ Biomass Stove Safety Protocol BSSP 1.1 Protocol (English)
  8. ↑ ESMAP (2015): The State of the Global Clean and Improved Cooking Sector. https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf
  9. ↑ http://www.scientificamerican.com/article/improved-cookstoves-little-reduce-harmful-indoor-emissions/
  10. ↑ https://en.wikipedia.org/wiki/Cook_stove#Advanced_biomass_cookstoves
  11. ↑ Practical Action (2013): Technical Brief. Gasifier Stoves - Advanced Biomass Stoves. http://answers.practicalaction.org/our-resources/item/gasifier-stoves-advanced-biomass-stoves
  12. ↑ Global Alliance for Clean Cookstoves, http://cleancookstoves.org/technology-and-fuels/stoves/
  13. ↑ http://carbonfinanceforcookstoves.org/about-cookstoves/cookstoves-and-fuels/


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